The present invention relates to a light fixture with a submersible enclosure for an electric lamp, especially for a High Intensity Discharge (HID) lamp, and, more particularly, to a light fixture that prevents undesirably high voltages from developing.
The use of HID lamps for lighting swimming pools has proven to be an attractive, efficient and long-lived alternative to the use of incandescent and halogen lamps. However, due to the relatively high voltages that are either momentarily required for starting HID lamps or that may be present continuously in the event of a lamp failure, the application of HID lamps to pool lighting has been limited to fiberoptics, such as Fiberstars FS6000 and Fibersrtars Underground(trademark) fiberoptic systems sold by Fiberstars Incorporated of Fremont, Calif.
Fiberoptic lighting systems avoid the problem of high voltage by locating the light source at a location remote from the pool. Additionally, these HID fiberoptic illumination systems may be configured to chance color in a pleasing, continuous manner by simply including a color wheel. The latest HID systems are also extremely energy efficient, often providing the illumination of a 500-watt pool light but using only 75 watts of electrical power. Moreover, HID lights are often advertised as xe2x80x9clife of the poolxe2x80x9d illumination, typically lasting several times the life of a halogen or incandescent pool lamp. Unfortunately, because HID fiberoptic lighting systems require trenches to accommodate fiber (and in some cases to bury the illuminator) these HID fiberoptic systems are only practical for new construction pools where the installation is economically viable.
Unfortunately, the majority of existing illuminated pools use incandescent or halogen lights mounted in a xe2x80x9cnichexe2x80x9d in the pool wall, below the water line. If HID lamps could be made to operate in this underwater environment, then the considerable benefits of HID lighting systems could be made available to all pools where lighting is desired, and would not require not fiberoptics.
It would additionally be desirable, for both ballasted and non-ballasted electrical lamps or other devices contained in an enclosure submersed in water, to prevent undesirably high voltages while keeping manufacturing costs low.
An exemplary embodiment of the invention provides a light fixture with a submersible enclosure for a gas discharge lamp such as an HID lamp. The fixture includes a ballast for supplying power to the lamp. A submersible enclosure seals the lamp from water in normal operation. In a first embodiment, the fixture includes a water-sensitive circuit having a conductance that increases in response to water that leaks into the enclosure for conducting current from the ballast and limiting the ballast voltage. In a second embodiment, the submersible enclosure contains a hot or common power lead for supplying power to an electrical load such as a lamp ballast, a non-ballasted lamp or a color wheel. The power lead includes a fuse region that corrosively reacts in the presence of leaked water in the container, so as to sufficiently wither away the fuse region and terminate power to the load. The first and second embodiments may be advantageously combined.
The foregoing light fixtures can beneficially avoid undesirably high voltages for a lamp ballast, a non-ballasted lamp or other electrical load. For an HID lamp in particular, a light fixture can be long-lived and economical.